I. Technical Field
The present invention relates to a disk brake suitably used to apply braking force to a vehicle, for example, an automobile.
II. Description of the Related Art
In general, a disk brake provided on a vehicle, e.g. an automobile is arranged as follows. When the driver of the vehicle or the like conducts a braking operation, inner and outer friction pads are pressed against both sides of a disk, thereby applying braking force to the disk (for example, see Japanese Patent Application Publication No. 2003-222171).
This type of conventional disk brake includes a mounting member secured to a non-rotating part of a vehicle. The mounting member has a pair of arms spaced apart from each other in the rotational direction of a disk. The pair of arms extends over the outer periphery of the disk in the axial direction of the disk. The arms are provided with pad guides formed, for example, from U-grooves.
A caliper is provided on the arms of the mounting member slidably in the axial direction of the disk. A pair of friction pads is slidably fitted in the pad guides of each arm. The friction pads are adapted to be pressed against both sides of the disk by the caliper. Two (for example) pad springs are attached respectively to the arms of the mounting member to resiliently support the pair of friction pads between the arms and to guide the friction pads in the axial direction of the disk.
Each pad spring is formed in a U shape as a whole from a resilient metal plate, for example, and disposed to extend over the outer periphery of the disk in the axial direction thereof from one (inner) side to the other (outer) side of the disk. The pad spring has a pair of guide plates positioned at the inner and outer sides, respectively, of the disk and fitted into the respective pad guides of the mounting member and a connecting plate extending over the outer periphery of the disk in the axial direction thereof and connected at both ends thereof to the pair of guide plates.
The guide plates resiliently support the friction pads, respectively, in the pad guides of the mounting member, thereby suppressing rattling of the friction pads and allowing smooth sliding displacement thereof. The connecting plate integrally connects together the inner and outer guide plates.
The above-described conventional technique uses substantially U-shaped pad springs to support the inner and outer friction pads. This conventional structure, however, involves some problems arising as the slidability of the friction pads relative to the pad springs deteriorates with age. That is, if the friction pads are caused to return away from the disk due to run-out of the disk rotating at idle during non-braking operation, external forces are applied to the guide plates of each pad spring in directions in which the guide plates are pulled away from the disk, together with the friction pads returned away from the disk.
The external forces urge the guide plates of the pad spring to move away from each other, and act as forces that pull the opposite ends of the connecting plate away from each other. In this regard, if the strength and rigidity of the joints between the guide plates and the connecting plate are not sufficiently high, the joints are elastically deformed. The elastic deformation of the joints undesirably causes the friction pads to be always pressed toward the disk. The friction pads thus pressed may drag against the disk, which causes brake noise or judder. Thus, insufficient strength and rigidity of the joints between the guide plates and the connecting plate lead to degradation of the function and durability of the pad spring.
The present invention has been made in view of the above-described problems with the conventional techniques. Accordingly, an object of the present invention is to provide a disk brake capable of satisfactorily increasing the strength of pad springs to prevent deformation thereof and to improve the durability and reliability thereof without the need to substantially change the configuration and the like of the pad springs.